Production-Grade Multi-Party Computation (MPC) Implementation

A secure, scalable Web3-native implementation of Multi-Party Computation protocols for distributed key management and secure computation.

🏗️ Architecture Overview

                        MPC System Architecture
┌──────────────────────────────────────────────────────────────────┐
│                                                                  │
│  ┌──────────────┐   ┌──────────────┐   ┌──────────────┐          │
│  │ Participant  │   │ Participant  │   │ Participant  │          │
│  │     #1       │   │     #2       │   │     #3       │          │
│  └──────┬───────┘   └──────┬───────┘   └──────┬───────┘          │
│         │                  │                  │                  │
│         └────────────┬─────┘────────┬─────────┘                  │
│                      │              │                            │
│              ┌───────▼──────────────▼───────────┐                │
│              │        MPC Protocol              │                │
│              │         Coordinator              │                │
│              └───────┬───────────────┬──────────┘                │
│                      │               │                           │
│          ┌───────────▼─────┌─────────▼───────┐                   │
│          │                 │                 │                   │
│  ┌───────▼───────┐ ┌───────▼───────┐ ┌───────▼─────┐             │
│  │    DKG        │ │    TSS        │ │   Shamir    │             │
│  │  Protocol     │ │  Signing      │ │   Secret    │             │
│  └───────────────┘ └───────────────┘ │   Sharing   │             │
│                                      └─────────────┘             │
│                                                                  │
│   ┌─────────────────────────────────────────────────────────┐    │
│   │             Distributed Storage Layer                   │    │
│   ├─────────────┬─────────────┬─────────────────────────────┤    │
│   │   AWS S3    │ Cloudflare  │    In-Memory Storage        │    │
│   │ (with KMS)  │    R2       │                             │    │
│   └─────────────┴─────────────┴─────────────────────────────┘    │
│                                                                  │
└──────────────────────────────────────────────────────────────────┘

🚀 Features

Core Cryptographic Protocols

• Distributed Key Generation (DKG): Pedersen DKG for threshold key generation
• Threshold Signatures (TSS): Support for threshold ECDSA/EdDSA signatures
• Shamir Secret Sharing: Enhanced implementation with large field support
• Zero-Knowledge Proofs: Schnorr proofs, range proofs, and share verification

Security Features

• End-to-end encryption for all shares at rest
• Secure random generation using OS entropy
• Proactive secret sharing for key refresh
• Multi-cloud distribution for resilience
• Hardware security module (HSM) support via AWS KMS
• Zero-knowledge proof verification for all protocol steps

Storage & Infrastructure

• Multi-provider support: AWS S3, Cloudflare R2, In-memory
• Geographic distribution across regions
• Automatic failover and redundancy
• TTL-based expiration for temporary shares
• Encrypted metadata storage

📋 MPC Protocol Flow

Phase 1: Distributed Key Generation

sequenceDiagram
    participant P1 as Participant 1
    participant P2 as Participant 2
    participant P3 as Participant 3
    participant C as Coordinator

    P1->>C: Register for DKG
    P2->>C: Register for DKG
    P3->>C: Register for DKG
    
    C->>P1: Start DKG Protocol
    C->>P2: Start DKG Protocol
    C->>P3: Start DKG Protocol
    
    P1->>P2: Share s_12 + Commitment
    P1->>P3: Share s_13 + Commitment
    P2->>P1: Share s_21 + Commitment
    P2->>P3: Share s_23 + Commitment
    P3->>P1: Share s_31 + Commitment
    P3->>P2: Share s_32 + Commitment
    
    P1->>P1: Verify shares & commitments
    P2->>P2: Verify shares & commitments
    P3->>P3: Verify shares & commitments
    
    P1->>C: Public key share PK_1
    P2->>C: Public key share PK_2
    P3->>C: Public key share PK_3
    
    C->>C: Compute group public key
    C->>P1: Group public key PK
    C->>P2: Group public key PK
    C->>P3: Group public key PK

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Phase 2: Threshold Signing

sequenceDiagram
    participant P1 as Participant 1
    participant P2 as Participant 2
    participant C as Coordinator
    participant B as Blockchain

    Note over C: Message M to sign
    
    C->>P1: Request signature for M
    C->>P2: Request signature for M
    
    P1->>C: Nonce commitment R_1
    P2->>C: Nonce commitment R_2
    
    C->>C: Aggregate R = R_1 + R_2
    
    C->>P1: Send aggregated R
    C->>P2: Send aggregated R
    
    P1->>C: Partial signature s_1
    P2->>C: Partial signature s_2
    
    C->>C: Combine s = s_1 + s_2
    C->>C: Signature = (R, s)
    
    C->>B: Submit transaction with signature
    B->>B: Verify signature with PK

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🛠️ Installation

Prerequisites

• Rust 1.70+
• Node.js 18+ (for Cloudflare Workers)
• AWS CLI configured (optional)
• Cloudflare Wrangler CLI

Setup

# Clone the repository
git clone https://github.com/yourusername/multi-party-computation.git
cd multi-party-computation

# Install dependencies
cargo build --release

# Install Node dependencies for Cloudflare Workers
npm install

# Configure environment variables
cp .env.example .env
# Edit .env with your configuration

Environment Variables

# AWS Configuration
AWS_S3_BUCKET=mpc-shares-bucket
AWS_KMS_KEY_ID=your-kms-key-id
AWS_REGION=us-west-1

# Cloudflare Configuration  
CLOUDFLARE_ACCOUNT_ID=your-account-id
CLOUDFLARE_API_TOKEN=your-api-token
SHARES_BUCKET=your-r2-bucket
SHARES_METADATA=your-kv-namespace

# MPC Configuration
MPC_THRESHOLD=3
MPC_TOTAL_PARTICIPANTS=5
MPC_SESSION_TIMEOUT=3600

🧪 Testing

Run Unit Tests

cargo test

Run Integration Tests

cargo test --test integration_tests

Run Benchmarks

cargo bench

Test Coverage

cargo tarpaulin --out Html
open tarpaulin-report.html

📊 Performance Benchmarks

Operation	Time (ms)	Throughput
DKG (5 participants)	120	8.3 ops/sec
Threshold Sign (3-of-5)	45	22.2 ops/sec
Shamir Split (256-bit)	2.3	434 ops/sec
Shamir Combine (3 shares)	1.8	555 ops/sec
ZKP Generation	0.9	1111 ops/sec
ZKP Verification	0.6	1666 ops/sec

🔐 Security Considerations

Threat Model

• Honest-but-curious adversaries: Protocol is secure against passive adversaries
• Byzantine failures: Tolerates up to (n-1)/2 malicious participants
• Network attacks: All communication is encrypted with TLS 1.3
• Storage compromise: Individual share compromise doesn't reveal secret

Security Measures

1. Cryptographic security:

   • 256-bit security level
   • Curve25519 for elliptic curve operations
   • SHA3-256 for hashing
   • ChaCha20-Poly1305 for authenticated encryption

2. Operational security:

   • Regular key rotation (daily by default)
   • Audit logging for all operations
   • Rate limiting on API endpoints
   • IP allowlisting for participants

3. Infrastructure security:

   • Multi-region deployment
   • Hardware security module integration
   • Zero-trust network architecture
   • Automated security scanning

🚢 Deployment

Deploy to Cloudflare Workers

# Build the Worker
npm run build

# Deploy to Cloudflare
wrangler publish

# Verify deployment
curl https://your-worker.workers.dev/health

Deploy to AWS Lambda

# Build for Lambda
cargo lambda build --release

# Deploy with SAM
sam deploy --guided

Docker Deployment

# Build Docker image
docker build -t mpc-service .

# Run container
docker run -p 8080:8080 \
  -e AWS_S3_BUCKET=your-bucket \
  -e MPC_THRESHOLD=3 \
  mpc-service

📖 API Documentation

POST /vault

Store a secret using MPC

Request:

{
  "user_pubkey": "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
  "encrypted_private_key": "base64_encrypted_key",
  "metadata": {
    "threshold": 3,
    "total_shares": 5,
    "regions": ["us-west-1", "eu-west-1"],
    "key_version": 1
  },
  "signature": "signature_base58"
}

Response:

[
  {
    "provider": "Aws",
    "region": "us-west-1",
    "identifier": "shares/uuid/share-1"
  },
  // ... more storage locations
]

GET /vault/:key_id

Retrieve shares for reconstruction

POST /sign

Sign a transaction using threshold signatures

🏗️ Project Structure

multi-party-computation/
├── src/
│   ├── crypto/           # Cryptographic protocols
│   │   ├── mod.rs        # Core crypto utilities
│   │   ├── dkg.rs        # Distributed Key Generation
│   │   ├── mpc.rs        # MPC coordination
│   │   ├── shamir.rs     # Shamir Secret Sharing
│   │   ├── threshold_signatures.rs  # TSS implementation
│   │   └── zkp.rs        # Zero-knowledge proofs
│   ├── storage/          # Storage providers
│   │   ├── aws.rs        # AWS S3 with KMS
│   │   ├── cloudflare.rs # Cloudflare R2
│   │   └── memory.rs     # In-memory storage
│   ├── api/              # API routes
│   ├── processing/       # Business logic
│   └── lib.rs            # Entry point
├── tests/
│   ├── integration_tests.rs
│   └── crypto_tests.rs
├── Cargo.toml
└── README.md

📚 References

• Shamir's Secret Sharing
• Threshold Signatures Explained
• Distributed Key Generation
• MPC Alliance

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Built with ❤️ using Rust and modern cryptography